Changing the one line bash script install to support multiple platforms

[pottekkat]

Recently the bash script to install mesheryctl and start Meshery was updated to allow the users specify a platform to deploy Meshery to (Docker and Kubernetes).

Users are able to pass in the flags as shown below(this is a work around)-

But, if the user does not specify a platform, it will throw an error(which it should not)-

These errors and workarounds are there because with the current structure of the one-line installer- curl -L https://git.io/meshery | bash -, we would not be able to pass in flags or get an input from the user.

The error "Invalid platform: " is because, when the user does not specify a platform, the bash script reads from the standard input. But, this is already taken up by the script hence causing the platform to be " " empty.

This can be fixed by changing the one liner as shown below-

We can use the -p flag to pass in the platform.

And, if the user does not specify a platform, it will prompt the user to enter a platform and validates it-

This discussion is to decide whether we should switch to the new one liner that I'm proposing-

For Docker-

bash -c "$(curl -L https://git.io/meshery)" -- -p docker

For Kubernetes-

bash -c "$(curl -L https://git.io/meshery)" -- -p kubernetes

Without specifying platform and prompting the user-

bash -c "$(curl -L https://git.io/meshery)"

Please share what you think and how we should proceed.

[leecalcote]

Alternatively, we update all references to the deprecated one-liner, so that the PLATFORM var is "always" included and when it is not included (for whatever reason) that the user is prompted for their desired platform. To assist in avoiding broken programmatic invocations of this script, a helpful return message could point out that no "PLATFORM" preference was provided.

Changing to from curl piped to bash seems like a bigger change than is necessary. Is your primary motivation here to avoid having to update existing script invocations; to avoid breaking those?

[pottekkat]

@dhruv0000 that would mean having multiple bash scripts right? One for each platform?

[hexxdump]

@dhruv0000 that would mean having multiple bash scripts right? One for each platform?

yes, does not make sense to have multiple scripts for multiple platforms, where most of the instructions are same.

[hexxdump]

If the user neglects to include PLATFORM, we indeed prompt the user. But this prompt will always fail because of this.

Inorder to handle missing platform, we have to move away from piping the script to bash. We cannot use interactive prompt and piping the script because both use the same standard input to read.

Hence, what this change will give is the ability to have interactive prompts.

@navendu-pottekkat , if we plan to move away from pipe, we could achieve the user prompt with the two commands syntax I mentioned earlier.
curl -L https://git.io/meshery -o meshery; PLATFORM=docker ./meshery -- for Docker platform
curl -L https://git.io/meshery -o meshery; PLATFORM=kubernetes ./meshery -- for kubernetes platform
curl -L https://git.io/meshery -o meshery; ./meshery -- prompts for user input

[devansh42]

I think, we can't use this syntax, as this requires meshery to be an executable file.

[devansh42]

Actually, Piping is quite difficult to understand, it just complicates a simple command, and as Lee said that PLATFORM and --p are equivalent in some nature and both would have some consequences if omitted by user. But non-pipe version can help us to extend the functionality of the installer in the future. Suppose in the future we add some new options then for the piped version it'd require to add new variables for each of them that will increase the cognitive complexity of the command, where non-piped version looks pretty mainstream, we can add many options with small argument name.
e.g. -p is easy to use and remember than PLATFORM or -n is simpler than DEPLOY_MESHERY.