How to replace variables of JSON file in Team Services? - azure-devops

Question

I'm stuck with a release variable substitution of an angular project. I have a settings.json file which I would like to replace some variables:
{
test : "variable to replace"
}
I tried to find some custom task on the marketplace but all of the tasks seems to work only with xml files for the web.config.

Answer 1

I use the "Replace tokens" from the Marketplace https://marketplace.visualstudio.com/items?itemName=qetza.replacetokens
You define the desired values as variables in the Release Definition and then you add the Replace Tokens task and configure a wildcard path for all target text files in your repository where you want to replace values (for example: **/*.json). The token that gets replaced has configurable prefix and postfix (default are '#{' and '}#'). So if you have a variable named constr you can put in your config.json
{
"connectionstring": "#{constr}#"
}
and it will deploy the file like
{
"connectionstring": "server=localhost,user id=admin,password=secret"
}

Answer 2

The IIS Web App Deploy Task in VSTS Releases has JSON variable substitution under *File Transforms & Variable Substitution Options.
Provide a list of json files and JSONPath expressions for the variables that need replacing
For example, to replace the value of ‘ConnectionString’ in the sample below, you need to define a variable as ‘Data.DefaultConnection.ConnectionString’ in the build/release definition (or release definition’s environment).
{
  "Data": {
    "DefaultConnection": {
      "ConnectionString": "Server=(localdb)\SQLEXPRESS;Database=MyDB;Trusted_Connection=True"
    }
  }
}

Answer 3

You can add a variable in release variables Tab, and then use PowerShell task to update the content of your settings.json.
Assume the original content is
{
test : "old
}
And you want to change it to
{
test : "new"
}
So you can replace the variable in json file with below steps:
1. Add variable
Define a variable in release variable tab with the value you want to replace with (variable test with value new):
2. Add PowerShell task
Settings for powershell task:
Type: Inline Script.
Inline Script:
# System.DefaultWorkingDirectory is the path like C:\_work\r1\a, so you need specify where your appsettings.json is.
$path="$(System.DefaultWorkingDirectory)\buildName\drop\WebApplication1\src\WebApplication1\appsettings.json"
(Get-Content $path) -replace "old",$(test) | out-file $path