Environment variables apparently not being passed to a systemd service invocation

Here is the case:

I am writing a go program.

At some point, the program calls terragrunt cli, via os.Exec().

The program is run on a machine having systemd version 232.

Up till know, I have been invoking terragrunt with some env vars exposed (required by terragrunt as we will see below)

These env vars are passed to the login process by /etc/profile.d/terragruntvars as in

export TF_VAR_remote_state_bucket=my-bucket-name

So when I run in my terminal say terragrunt plan and by the appropriate interpolation in my tf / hcl files, I get something like (this is a debug level output, showing the actual terraform invocation terragrunt ends up performing)

terraform init -backend-config=my-bucket-name ...(more flags following)

My go program (invoking terragrunt cli via os.Exec()) runs perfectly via go run main.go

I decide to make this a systemd service as in

[Service]
ExecStart=/bin/sh -c myprogram
EnvironmentFile=/etc/myprogram/config
User=someuser
Group=somegroup

[Install]
WantedBy=multi-user.target

The program started failing miserably. By searching the root case I found out that the TF_VAR_* variables where never passed to the service when running, so the terraform command ended up being like

terraform init -backend-config=(this is empty, nothing here)

I thought that by explicitly invoking the service via bash, i.e. by making ExecStart=/bin/sh -c myprogram this would address the problem.

Here come the weird(est) parts.

Adding these vars to EnvironmentFile=/etc/myprogram/config did not have any effect in the terragrunt execution. When I say no effect, I mean the variables did become available to the service, however the command is still broken, i.e.

terraform init -backend-config=(this is empty, nothing here)

However, the TF_VAR_* variables ARE there. I added an os.Exec("env") in my program and it did print them.

This has been driving me nuts so any hint about what might be causing this would be highly appreciated.

Just like a shell will not pass it's process ENV VAR's on to child processes:

$ X=abc
$ bash -c 'echo $X'   # prints nothing

unless you export the environment variable:

$ export X
$ bash -c 'echo $X'   # abc

similarly with systemd and when using EnvironmentFile, to export environment variables, use PassEnvironment e.g.

PassEnvironment=VAR1 VAR2 VAR3

From the docs:

> PassEnvironment=
> Pass environment variables set for the system service manager to executed processes.
> Takes a space-separated list of variable names...