Use YAML with variables

Question

Are variables within YAML files possible  For example   theme    name  default   css path  compiled themes  theme name   layout path  themes  theme name   In this example  how can theme  name  default be used in other settings  What is the syntax

User · Answer

This is an old post  but I had a similar need and this is the solution I came up with   It is a bit of a hack  but it works and could be refined   require  erb  require  yaml   doc    lt  lt -EOF   theme    name  default   css path  compiled themes  lt    data  theme    name     gt    layout path  themes  lt    data  theme    name     gt    image path   lt    data  theme    css path     gt  images   recursive path   lt    data  theme    image path     gt  plus one more EOF  data   YAML  load  ---    doc   template   ERB new data to yaml   str   template result binding  while   lt       gt   match str     nil   str   ERB new str  result binding  end  puts str   A big downside is that it builds into the yaml document a variable name  in this case   data   that may or may not exist   Perhaps a better solution would be to use   and then substitute it with the variable name in Ruby prior to ERB   Also  just tested using hashes2ostruct which allows data theme name type notation which is much easier on the eyes   All that is required is to wrap the YAML  load with this  data   hashes2ostruct YAML  load  ---    doc     Then your YAML document can look like this  doc    lt  lt -EOF   theme    name  default   css path  compiled themes  lt    data theme name   gt    layout path  themes  lt    data theme name   gt    image path   lt    data theme css path   gt  images   recursive path   lt    data theme image path   gt  plus one more EOF

User · Answer

This is how I was able to configure yaml files to refer to variable  I have values yaml where we have root level fields which are used as template variables inside  values yaml  values yaml          databaseUserPropName  spring datasource username   databaseUserName  sa           secrets      type  Opaque       name  dbservice-secrets       data          - name   quot     Values databaseUserPropName    quot            value   quot     Values databaseUserName    quot           When referencing these values in secret yaml  we would use tpl function using syntax    tpl TEMPLATE STRING VALUES     secret yaml  when using inside range i e iteration      range  Values deployments secrets data           tpl  name        quot    tpl  value      quot       end     when directly referring as variable      tpl  Values deployments secrets data name           tpl  Values deployments secrets data value          - this is global variable and will always point to the root context   - this variable will point to the root context based on where it used

User · Answer

if your requirement is like parsing an replacing multiple variable and then use it as a hash or anything then you can do something like this require  yaml  require  json  yaml   YAML load file  quot xxxx yaml quot   blueprint   yaml to json     var a   quot xxxx quot   var b   quot xxxx quot   hash   JSON parse blueprint   inside the yaml just put variables like this  quot   var a  quot

User · Answer

I had this same question  and after a lot of research  it looks like it s not possible   The answer from cgat is on the right track  but you can t actually concatenate references like that   Here are things you can do with  variables  in YAML  which are officially called  node anchors  when you set them and  references  when you use them later    Define a value and use an exact copy of it later   default   amp default title This Post Has No Title title   default title     or    example post   amp example   title  My mom likes roosters   body  Seriously  she does  And I don t know when it started    date  8 18 2012 first post   example second post    title  whatever  etc    For more info  see this section of the wiki page about YAML  http   en wikipedia org wiki YAML References  Define an object and use it with modifications later   default   amp DEFAULT   URL           stooges com   throw pies    true     stooges    amp stooge list     larry   first stooge     moe     second stooge     curly   third stooge  development     lt  lt    DEFAULT   URL       stooges local   stooges       shemp  fourth stooge  test     lt  lt    DEFAULT   URL     test stooges qa   stooges        lt  lt    stooge list     shemp  fourth stooge   This is taken directly from a great demo here  https   gist github com bowsersenior 979804

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Rails   ruby frameworks are able to do some templating     it s frequently used to load env variables        fooz yml   foo      bar   lt     ENV  some var    gt    No idea if this works for javascript frameworks as I think that YML format is superset of json and it depends on what reads the yml file for you   If you can use the template like that or the  lt  lt   gt  gt  or the       styles depending on your reader  after that you just      In another yml file        boo yml  development    fooz  foo   Which allows you to basically insert a variable as your reference that original file each time which is dynamically set   When reading I was also seeing you can create or open YML files as objects on the fly for several languages which allows you to create a file  amp  chain write a series of YML files or just have them all statically pointing to the dynamically created one

User · Answer

After some search  I ve found a cleaner solution wich use the   operator    In your YAML file     key    This is the foobar var     foobar     In your ruby code     require  yaml   file   YAML load file  your file yml    foobar    Hello World    content   file  key   modified content   content      foobar   gt  foobar    puts modified content   And the output is     This is the foobar var   Hello World       As  jschorr said in the comment  you can also add multiple variable to the value in the Yaml file    Yaml    key    The foo var is   foo  and the bar var is   bar       Ruby           foo    FOO  bar    BAR        modified content   content      foo   gt  foo   bar   gt  bar     Output     The foo var is FOO and the bar var is BAR

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