Show HN: Curl


170 points | by kureikain 156 days ago


  • kureikain 156 days ago

    From time to time, I want a quick tool to help me compare EC2 instances price. works great but it's somewhat slow and didn't have a way to just `curl` from terminal.

    So I develop this small tool which you can do thing like

    • JimDabell 156 days ago

      Are you manually detecting Curl specifically? If I use anything other than Curl, e.g. HTTPie or wget, I get the HTML page, even if I provide an `Accept: text/plain` request header. If I use one of those tools and spoof the Curl user agent string, I get the text/plain response. You should probably just look at the Accept request header, it’s there specifically so clients can tell you what kind of response they want.

      • kureikain 156 days ago

        Great idea.

        I just implement it:

        Now by default it's text mode, so request by http client library or tool like curl, wget, httppie all get text bersion.

        Only when detecting `Accept` contains `html` and user agent is safari/chrome/firefox etc it send html version.

        • karmakaze 156 days ago

          There should be no reason to check user agent if already checking `Accept`. That's usually more for browser quirks or allow/blocking.

        • jasonjayr 156 days ago

          There should be a new mime type for this: text/x-ansi

          • gruez 156 days ago

            but why "ansi"? ANSI is only an encoding. You can have html that's in ansi, and you can have something like OP's that's not in ansi (eg. if you add emojis).

            • geofft 156 days ago

              This is "ANSI" as in ANSI X3.64 escape sequences, not "ANSI" as in a character encoding. You can output color to curl on an ANSI-compatible terminal but not to something expecting actual plain text like a browser.

              • skissane 155 days ago

                I think text/ecma48 would be a better name. There are lots of ANSI standards. (I guess text/ansi-x3.64 might also work, but text/ecma48 seems simpler.)

                • jasonjayr 155 days ago

                  Yes, I should have been more specific. text/x-term-${TERM} probably would be better, since it could be any number of terminal types...

              • nitrogen 156 days ago

                You might be thinking of ASCII?

                • gruez 156 days ago
                  • nitrogen 155 days ago

                    From the wiki: "The phrase ANSI character set has no well-defined meaning and has been used to refer to the following, among other things"

                    So if you are thinking of CP-437 or Windows-1252 I suppose that's fair, but generally in the context of terminal apps "ANSI" without qualification refers to the escape sequences.

                    Now I am curious though, did ANSI the standards body have any official character encoding standards?

          • simedw 156 days ago

            Useful tool!

            Do you not need to escape the ampersand in the second example? otherwise bash will run it in the background and skip the `filters=t2,m4` part.

            • bdcravens 156 days ago

              Yes, but many terminals will escape it for you if you paste in.

            • brodouevencode 156 days ago

              And it has to be infinitely better than using the pricing API.

              • tinhspace 156 days ago

                Thank you so much. Going to try this one, very useful tool.

              • kissgyorgy 156 days ago

                You can do cool things with this very quickly. For example, I always wondered the price differences between different regions, you can compare two instance prices quickly:

                    diff -u <(curl -sS "" | grep "t3.large" ) <(curl -sS "" | grep "t3.large")
                • echeese 156 days ago

                  The prices column is sorted lexicographically, instead of numeric, i.e. 1, 10, 2

                  • GlitchMr 156 days ago

                    This can be dealt with by using a different comparison function, say `.sort((a, b) => a.localeCompare(b, 'en', {numeric: true}))`.

                    • ohashi 156 days ago

                      They all are

                      • kureikain 155 days ago

                        I fixed this sorting issue :-). Give it another try.

                    • solatic 156 days ago

                      Color output seems to be tuned for dark terminal backgrounds. Memory, vCPUs, and Storage are nearly unreadable on a white background.

                      • hnlmorg 156 days ago

                        I've moaned about this with other CLI tools as well. I wish trend of using RGB values in ANSI escape codes would die because as ugly as the 16*3 colour fields¹ are, they are at least customisable so people can use palettes that suite their terminal and eyesight.

                        You don't get any such opportunity if the developers hard code the colour values in (and it's worse with a tool like this because you can't even set an environmental variable to change the tools behaviour)

                        ¹ sixteen colours plus bright and dark variants

                        • ASVVVAD 156 days ago

                          Can you link me to a way to use colours that change with the terminal colour preset? I haven't come across anything like that or maybe didn't pay attention. It would be really helpful

                          You said you can't even set an env variable to change them so I assume that there is an even better way?

                          • hnlmorg 156 days ago

                            Wikipedia has a good section on the different methods of describing colour:

                            I've got some Go code that you can reuse if you want to the escape codes in Go:

                            Just bare in mind that any numbers you see in documentation are sent as ASCII values rather than integers. eg `ESC[31m` (red text) should be sent to the terminal as

                                []byte{  //
                                    27,  // ESC character code
                                    91,  // '['
                                    51,  // '3'
                                    49,  // '1'
                                    109, // 'm'
                            Though, as you know, most languages will have some syntactic sugar to translate characters to their ASCII values, eg

                                'm' == 109
                                Asc("m") == 109
                            so at least you don't have to write all those values by hand.
                            • ASVVVAD 156 days ago

                              Thanks for the explanation and the snippets ^^

                            • kristopolous 156 days ago

                              On Linux, in X, you can use xresources. Otherwise there's termcap

                              • ASVVVAD 156 days ago

                                totally forgot about xresources! thanks for the reminder

                          • numlock86 156 days ago

                            Thanks for the heads up. Colored output in terminal programs is a no go.

                            • kolinkorr839 156 days ago

                              I have a white background too. Is there a workaround for this?

                              • kureikain 156 days ago

                                I disable the colorize so it should be your default terminal now.

                              • allis10 156 days ago

                                Sounds like you played a stupid game and won a stupid prize.

                            • shitloadofbooks 156 days ago

                              I really like this, but the horizontal lines are not helpful at all and just double the number of lines for no benefit.

                              You can obviously

                                  curl | grep -v ─
                              but I'm not sure I want to do that every time and I'm not exactly sure why, but when I do that, I can't select the entire row, only a column at a time (zsh on iTerm 2).
                              • kureikain 156 days ago

                                I turn off the color :-). And I must say it much nicer without color. Thank you.

                                • anamexis 156 days ago

                                  I also really like this, and have some feedback:

                                  I don't find the colors useful. They aren't contextual at all, it's just certain columns have certain colors, for no apparent reason.

                                • cheeaun 156 days ago

                                  Is this open sourced?

                                  I personally try looking into implementing a curl "interface" to one of my projects, realised that it actually need to check the user-agent (of curl and a plethora of curl alternatives) which I find kind of weird...

                                  • codetrotter 156 days ago

                                    > realised that it actually need to check the user-agent

                                    Like someone suggested for the featured page as well, I recommend you make use of the accept header.

                                    For example, assuming your interface is outputting freeform text (since the goal was to have something readable in terminal), you could use something like this:

                                        Accept: text/; version=1.0
                                    (Substitute “myproject” with the actual name of your project.)
                                    • kureikain 156 days ago

                                      Hey, yes it's 100% open source.


                                      The reason it check `curl` agent is because it share the same endpoint (root url) for both of `curl` page and browser version(the one with dropdown, grid etc)

                                  • soerface 156 days ago

                                    Neat! The prices are without currency symbols - I guess it's always USD? Or maybe dependent on the region…? Would be nice if the $ symbol is printed, and even better if I could see the prices of my european servers in european currency - maybe add a param to select the currency?

                                    It would be very helpful if you would support the `Accept: application/json` header. This way, we could use it in combination with jq to do arbitrary filtering:

                                        curl -L -H "Accept: application/json" | jq .
                                    • YoavR7 156 days ago

                                      Cool! You should probably add http support and not only https. Writing `curl` is easier than `curl`

                                      • saurik 156 days ago

                                        For HTTPS to truly be meaningful we need to stop supporting HTTP as an on-ramp, to prevent people from just hijacking that initial unencrypted connection and sending anything they want.

                                        • Znafon 156 days ago

                                          If you MITM and the user agent send an HTTP request for it does not matter whether the webserver supports HTTP or not, you can send a fake HTTP response either way.

                                          • hnlmorg 156 days ago

                                            That was the GPs point.

                                          • mschuster91 156 days ago

                                            Anyone who likes to prevent that can submit their site to the HSTS preload list. Chrome, Firefox and Edge use a shared one, the only two relevant other agents (Safari and curl) unfortunately don't though.

                                            • flatiron 156 days ago

                                              This is about curl though.

                                            • xxpor 156 days ago

                                              (speaking only for myself, not my employer)

                                              I truly do not care if someone goes through the effort to MITM my curl of to inject fake prices or something like that.

                                              There's nothing here that's going to be executed, it'll just be printed or grepped.

                                              In theory you could exploit a 0 day in curl or my terminal or something like that, but I think if you truly think about the risks and tradeoffs here it's really not worth worrying about.

                                              If curl had an hsts list to make this irrelevant that'd also be cool.

                                              • toyg 156 days ago

                                                > There's nothing here that's going to be executed

                                                ... yet.

                                                Imagine someone using it to find "the biggest size available under $1" and then taking that value to execute some other script.

                                            • hnlmorg 156 days ago

                                              These days curl should probably default to https. Or at least give you an environmental variable where you can define the default protocol (libcurl does offer something similar:

                                            • shawabawa3 156 days ago

                                              curl -L works for just 2 extra chars

                                            • baliex 156 days ago

                                              Could you update the `...&filter...` example to wrap the URL in quotes so that the `&` isn't interpretted by the shell as sending the process to the background?

                                              • kureikain 156 days ago

                                                Ah crap, yes, going to update it.

                                                • elemenophy 156 days ago

                                                  this is an issue of ZSH.

                                                  • hnlmorg 155 days ago

                                                    That is a POSIX standard and not something specific to zsh

                                                    • wolfgang42 156 days ago

                                                      No, plain sh also uses the ampersand as a job control operator.

                                                  • nnx 156 days ago

                                                    Interesting tool. Would be really useful if it supported Spot prices, which are even more of a PITA to find using Amazon’s UI.

                                                    • kureikain 156 days ago

                                                      Yes, it isn't that hard to support Spot prices but the price change too often so I have to scrape it for every 5 minutes. Right now, I haven't had the automation to run this yet but it's doable and my pain point too =)

                                                    • kureikain 156 days ago

                                                      Wow, thank you for the feedback. I'm going to implement lot of features suggest in this page.

                                                      Since I cannot edit original comment, yes, the site is open source:

                                                      • dxxvi 156 days ago

                                                        Can I be sure that the prices from this endpoint are accurate (i.e. if Amzn changes the prices, this endpoint will reflect that change)? Off-topic: if I request a spot instance, is there any way (API/cli) to know how much Amzn charges me every hour for that instance?

                                                        • gen220 156 days ago

                                                          I've built something like this in the past (I was running a beefy server for my friends, and wanted them to know how much it was costing us at an hourly rate, before they ran it for 3 weeks straight).

                                                          It's definitely possible and not very challenging, but the API Documentation for prices was pretty weak when I built it (a year or two ago, written in Go if it makes a difference). The google cloud prices API was similarly gross. It was kinda fun, but I wouldn't enjoy maintaining that code. In reality, it turns out that $/hour isn't a super straightforward metric (there are many dimensions that go into it), so it's not super straightforward to query.

                                                          • kureikain 156 days ago

                                                            I think the price is accurate. It's fetched directly from this Amazon endpoint.

                                                            I'm going to add spot instance. Will just need to figure out what URL AWS is fetching

                                                          • zkirill 156 days ago

                                                            Super! It would be great to see price per month as well.

                                                            • css 156 days ago

                                                              Very neat. Anyone know why

                                                                  curl -s | grep 't2'
                                                              would work, but

                                                                  curl -s | grep 'm4'
                                                              does not? Both commands work if I write the curl result to a file, but when I pipe from curl, the pattern `m4` matches all instances of the number 4.
                                                              • wolfgang42 156 days ago

                                                                It’s not matching every number 4, just the ones at the start of a column. The m is coming from “ESC[31m”, the escape code used to set the color of the text in the column.

                                                                • kureikain 156 days ago

                                                                  Thank you, this is a bug.

                                                                  The color code for blue is `"\033[34m` so it always match m4 for anything :(.

                                                                  Just push a fix by disabling color as suggestion in here as well

                                                                  • css 156 days ago

                                                                    Ah, got it, thanks for the clarity.

                                                                • xhrpost 156 days ago

                                                                  Neat, didn't realize how much the options for ec2 have grown over time. Can those instances with 100Gbps networking actually push that to upstream transit (ie. the Internet)? Or is that mostly for internal network communication between instances and other AWS services?

                                                                  • nine_k 155 days ago

                                                                    The examples miss the opening quote before the URLs.


                                                                    • ryanmccullagh 155 days ago

                                                                      Nice list. Recently, I loaded all the prices into an Excel document to make things easier for projecting costs and determining prices. I always use the following formula for estimating monthly costs on Amezmo.

                                                                      $Hourly * 750

                                                                      750 being the number of hours in 1 month.

                                                                      • afshinmeh 156 days ago

                                                                        Nice! thanks for using :)

                                                                        • m00dy 156 days ago

                                                                          now curl is the new black ? :) This is not my first time that I see curl based services.

                                                                          • alexellisuk 156 days ago

                                                                            Could you have it retain the sort order when changing region?

                                                                            • kolinkorr839 156 days ago

                                                                              Is there a way to show the output in json format?

                                                                              • mike-cardwell 156 days ago

                                                                                Would be nice if both of these work (they don't):

                                                                                curl -H 'Accept: application/json'


                                                                                • kureikain 156 days ago

                                                                                  It should work that way now :-). Thanks for suggestion.

                                                                                • kureikain 156 days ago

                                                                                  Per suggest by mike-cardwell, I implemented this:

                                                                                    curl -H 'Accept: application/json'
                                                                                    curl ''
                                                                                    curl ''
                                                                                • JosephRedfern 156 days ago

                                                                                  Very hand. Can you add sorting?

                                                                                  • hnlmorg 156 days ago

                                                                                    ...or remove the pretty line glyphs so this tool can be used in a normal CLI pipeline (eg `sort`)

                                                                                    • certifiedloud 156 days ago

                                                                                      You can always pipe to sort

                                                                                    • kstrauser 156 days ago

                                                                                      Bravo. This is really lovely!

                                                                                      • vmception 156 days ago

                                                                                        I like this trend