Show HN: Curl


170 points | by kureikain 4 days ago


  • kureikain 4 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 4 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 4 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 4 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 4 days ago

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

          • gruez 4 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 4 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 3 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 3 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 4 days ago

                You might be thinking of ASCII?

                • gruez 4 days ago
                  • nitrogen 4 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 4 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 4 days ago

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

            • brodouevencode 4 days ago

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

              • tinhspace 4 days ago

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

              • kissgyorgy 4 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 4 days ago

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

                  • GlitchMr 4 days ago

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

                    • ohashi 4 days ago

                      They all are

                      • kureikain 4 days ago

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

                    • solatic 4 days ago

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

                      • hnlmorg 4 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 4 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 4 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 4 days ago

                              Thanks for the explanation and the snippets ^^

                            • kristopolous 4 days ago

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

                              • ASVVVAD 4 days ago

                                totally forgot about xresources! thanks for the reminder

                          • numlock86 4 days ago

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

                            • kolinkorr839 4 days ago

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

                              • kureikain 4 days ago

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

                              • allis10 4 days ago

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

                            • 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 4 days ago

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

                                • anamexis 4 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 4 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 4 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 4 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 4 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 4 days ago

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

                                      • saurik 4 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 4 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.

                                        • mschuster91 4 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.

                                        • xxpor 4 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 4 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 4 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 4 days ago

                                          curl -L works for just 2 extra chars

                                        • baliex 4 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 4 days ago

                                            Ah crap, yes, going to update it.

                                            • elemenophy 4 days ago

                                              this is an issue of ZSH.

                                              • hnlmorg 3 days ago

                                                That is a POSIX standard and not something specific to zsh

                                                • wolfgang42 4 days ago

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

                                              • nnx 4 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 4 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 4 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 4 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 4 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 4 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 4 days ago

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

                                                        • css 4 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 4 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 4 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 4 days ago

                                                                Ah, got it, thanks for the clarity.

                                                            • xhrpost 4 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?

                                                              • ryanmccullagh 4 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.

                                                                • nine_k 4 days ago

                                                                  The examples miss the opening quote before the URLs.


                                                                  • afshinmeh 4 days ago

                                                                    Nice! thanks for using :)

                                                                    • m00dy 4 days ago

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

                                                                      • alexellisuk 4 days ago

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

                                                                        • kolinkorr839 4 days ago

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

                                                                          • mike-cardwell 4 days ago

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

                                                                            curl -H 'Accept: application/json'


                                                                            • kureikain 4 days ago

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

                                                                            • kureikain 4 days ago

                                                                              Per suggest by mike-cardwell, I implemented this:

                                                                                curl -H 'Accept: application/json'
                                                                                curl ''
                                                                                curl ''
                                                                            • JosephRedfern 4 days ago

                                                                              Very hand. Can you add sorting?

                                                                              • hnlmorg 4 days ago

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

                                                                                • certifiedloud 4 days ago

                                                                                  You can always pipe to sort

                                                                                • kstrauser 4 days ago

                                                                                  Bravo. This is really lovely!

                                                                                  • vmception 4 days ago

                                                                                    I like this trend