I've recently started dealing with CF templates in my org what uses the following syntax.
metadata:
name: {{{MY_APP}}}-resources
Resources:
DBInstance:
Properties:
DBName: "{{{DB_NAME}}}_db_{{{NAMESPACE}}}"
EngineVersion: "{{{DB_ENGINE_VERSION}}}"
...
The variables are passed via a delivery.yaml . And the intention and operation works. I find the syntax confusing though and couldn't find a reference on the yaml spec.
VSCode RedHat's yaml extension complains about this line (and many other similar ones across the files):
name: {{{MY_APP}}}-resources
with the message:
Unexpected scalar at node end
My understanding so far after looking online is that the complain is due to the - symbol. It can cause ambiguity since if these values would come as numbers it could be missinterpreted as an operation. Several alternatives seems to satisfy the linter:
'{{{MY_APP}}}-resources'
${MY_APP}-resources
etc, etc
So a couple of questions:
what's up with the triple brackets? is that just for visuals or does it do sth different than single brackets.
What's the recommended way to do this given the AWS CF context?
Related
I am using IntelliJ and want to find a quick way to format a lot of yaml files from this:
something:
some:
thing:
enable: true
a:
b:
c: true
d:
e: false
to this:
something.some.thing.enable: true
a.b:
c: true
d.e: false
whereever possible. It is still valid syntax, but in the files in question, it is way better to read and often times, elements really just contain one value.
Is there an offline tool, plugin or maven/gradle build step I can use to achieve this?
It is still valid syntax
Yes, but it doesn't do what you think it does. d.e in YAML will simply load as string "d.e". There is no YAML logic that splits at the dot like you seem to assume.
Java Spring does some postprocessing that causes this to be loaded properly, see also this question. However, this does not work generally with YAML.
See this answer for a yq command that does something like this – however it will print a full path for each value and you probably don't want that. Doing what you want is probably too complex for yq, but not impossible to achieve.
Also mind that queries about finding external tools are off-topic on StackOverflow.
I saw a YAML file that includes some signs like $, ^. For $, I think it tries to get value from a JSON file. But for ^, I'm not sure about that.
I tried to search for the YAML syntax but cannot find the usage of those signs.
Could anyone point out where that usage from? Thanks a lot!
examples:
json: $.A.Documents[*]
input: ^.B.ID
YAML doesn't assign any special meaning to those characters. As far as YAML is concerned, they are simply part of the content.
Of course, the software loading that YAML can do anything with the loaded data – including inspecting the loaded scalars for $ and ^ and implementing some action on them.
While someone might be able to correctly guess which software expects a YAML file like the one you show, it would be vastly easier for you to check the context in which you found that YAML file. This should lead you to the information you seek – i.e., for which software that YAML file has been written. That software's documentation will then describe how those characters are processed.
I have an anchor as follows:
helm-install
docker-flags: &my_docker_flags
- "--network host"
- "--env KUBECONFIG=/tmp/admin.conf"
- "--env HOME=${env.HOME}"
- "--volume ${env.KUBECONFIG}:/tmp/admin.conf:ro"
- "--volume ${env.PWD}:${env.PWD}"
- "--volume ${env.HOME}/.helm:${env.HOME}/.helm"
- "--volume
${var.docker_config_basepath}:${var.docker_config_basepath}"
later I want to do:
docker-flags:
<<: *my_docker_flags
- "--env K8_NAMESPACE=${env.K8_NAMESPACE}"
But, the last line is flagged as bad indentation of a mapping entry YAML
The YAML merge key <<, defined here, is a feature defined for outdated YAML 1.1. It has never been part of the spec and thus its implementation is optional. Lots of YAML implementations implemented it and it remains a feature even while they get updated for YAML 1.2, which doesn't define this feature.
As a „key“, it is not a special syntax feature. Instead, much like the scalar true, it gets interpreted as something special because of its content. Supporting implementations will treat it according to the linked specification when it occurs as key in a mapping.
However, a sequence like the one you are showing is a different data structure: It contains a sequence of items. There is no place to put a merge key here, so you cannot use this feature in a sequence.
Generally, YAML is not a data processing language. << was and is an exception to that, there are no other processing features – neither for merging sequences, nor for different operations you would expect from a data processing language, like e.g. concatenation of strings.
For this reason, lots of tools that heavily use YAML, such as Ansible or Helm, include some kind of template processing for their YAML input files. While far from perfect, templating is currently the most versatile way to do data processing in a YAML file.
If the tool that reads your YAML doesn't provide you with a templating engine, your only option is to pre-process the YAML file manually, for example using a simple templating engine like mustache. Whether that is feasible depends of course on the context.
I'm working on a project where YAMLs are used (among other use cases) for storing synonym lists. A file may look a little like this:
- "streifen,gestreift"
- "fleeceoverall,fleeceanzug"- "federball,badminton"
- "hochgarage,parkgarage"
In this case - "federball,badminton" is on the same row as - "fleeceoverall,fleeceanzug" which causes the build of the application to fail with an error stating
Unexpected characters near "- "federball,badminton".
I tried to configure a code style profile for code inspections as mentioned here in the PhpStorm documentation:
https://www.jetbrains.com/help/phpstorm/customizing-profiles.html?keymap=secondary_default_for_macos
But I don't know what to adjust here. I using the IDE-Standard which looks like this for wrapping and braces (which I guess is what I'm looking for ;) :
I also took a look at validating my YAML against a JSON file as mentioned here: https://www.jetbrains.com/help/phpstorm/yaml.html# but ultimately I don't understand how this works :/
So I guess I'm a little lost on how to avoid the errors at build time beforehand and would love some advice!
So for my text parsing in C# question, I got directed at YAML. I'm hitting a wall with this library I was recommended, so this is a quickie.
heading:
name: A name
taco: Yes
age: 32
heading:
name: Another name
taco: No
age: 27
And so on. Is that valid?
Partially. YAML supports the notion of multiple consecutive "documents". If this is what you are trying to do here, then yes, it is correct - you have two documents (or document fragments). To make it more explicit, you should separate them with three dashes, like this:
---
heading:
name: A name
taco: Yes
age: 32
---
heading:
name: Another name
taco: No
age: 27
On the other hand if you wish to make them part of the same document (so that deserializing them would result in a list with two elements), you should write it like the following. Take extra care with the indentation level:
- heading:
name: A name
taco: Yes
age: 32
- heading:
name: Another name
taco: No
age: 27
In general YAML is concise and human readable / editable, but not really human writable, so you should always use libraries to generate it. Also, take care that there exists some breaking changes between different versions of YAML, which can bite you if you are using libraries in different languages which conform to different versions of the standard.
Well, it appears YAML is gone out the window then. I want something both human writable and readable. Plus, this C# implementation...I have no idea if it's working or not, the documentation consists of a few one line code examples. It barfs on their own YAML files, and is an old student project. The only other C# YAML parser I've found uses the MS-PL which I'm not really comfortable using.
I might just end up rolling my own format. Best practices be damned, all I want to do is associate a key with a value.
Try this(Online YAML parser).
You don't have to download anything or do something. Just go there, and copy & paste. That's it.
There appears to be a YAML validator called Kwalify which should give you the answer. You shoulda just gone with the String tokenizing, man. Writing parsers is fun :)
There is another YAML library for .NET which is under development. Right now it supports reading YAML streams. It has been tested on Windows and Mono. Write support is currently being implemented.
CodeProject has one at:
http://www.codeproject.com/KB/recipes/yamlparser.aspx
I haven't tried it too much, but it's worth a look.
You can see the output in the online yaml parser :
http://yaml-online-parser.appspot.com/?yaml=heading%3A%0D%0A+name%3A+A+name%0D%0A+taco%3A+Yes%0D%0A+age%3A+32%0D%0A%0D%0Aheading%3A%0D%0A+name%3A+Another+name%0D%0A+taco%3A+No%0D%0A+age%3A+27%0D%0A&type=json
As you can see, there is only one heading node created.
Just to make an explicit comment about it: You have a duplicate mapping key issue. A YAML processor will resolve this as a !!map, which prohibits duplicate keys. Not all processors enforce this constraint, though, so you might get an incorrect result if you pass an incorrect YAML stream to a processor.