Can't do module replacement with github forks

[francislavoie]

So I want to have a replacement like:

replace github.com/mholt/caddy-dynamicdns => github.com/francislavoie/caddy-dynamicdns caddyfile

So I try this:

xcaddy build --with github.com/mholt/caddy-dynamicdns=github.com/francislavoie/caddy-dynamicdns@caddyfile

But it does this:

...
2021/02/21 07:25:03 [INFO] exec (timeout=0s): /usr/local/go/bin/go get -d -v github.com/mholt/caddy-dynamicdns=github.com/francislavoie/caddy-dynamicdns@caddyfile
go get github.com/mholt/caddy-dynamicdns=github.com/francislavoie/caddy-dynamicdns@caddyfile: malformed module path "github.com/mholt/caddy-dynamicdns=github.com/francislavoie/caddy-dynamicdns": invalid char '='

This obviously isn't quite right, cause it never did the go mod edit -replace.

Next I tried without @caddyfile (my branch), and I get this:

2021/02/21 07:29:24 [INFO] Resolved relative replacement github.com/mholt/caddy-dynamicdns=github.com/francislavoie/caddy-dynamicdns to /root/github.com/francislavoie/caddy-dynamicdns
...
2021/02/21 07:29:24 [INFO] Replace github.com/mholt/caddy-dynamicdns => /root/github.com/francislavoie/caddy-dynamicdns
2021/02/21 07:29:24 [INFO] exec (timeout=10s): /usr/local/go/bin/go mod edit -replace github.com/mholt/caddy-dynamicdns=/root/github.com/francislavoie/caddy-dynamicdns
...
caddy imports
        github.com/mholt/caddy-dynamicdns: github.com/mholt/caddy-dynamicdns@v0.0.0-00010101000000-000000000000: replacement directory /root/github.com/francislavoie/caddy-dynamicdns does not exist

So xcaddy thinks that path is relative but it's not, it's a git repo.

I think to detect if it's relative, we should look if there's a . in front, so if you want to refer to something in the current dir then you do ./blah in the replacement. That should allow github module paths to work.

The workaround obviously for now is to git clone the relevant repo then use a relative path on that, but it would be nice so that people can easily test branches/PRs for plugins without cloning.

[mholt]

Hmm, wouldn't you just change the require dependency from github.com/mholt/caddy-dynamicdns to github.com/francislavoie/caddy-dynamicdns?

[francislavoie]

No because that would imply the master branch, but if it's not on the master branch that won't work.

[mholt]

Set the version of that require directive to another branch then?

[francislavoie]

What do you mean? What would the command look like?

[mholt]

require directives consist of a module name and a version:

github.com/mholt/acmez v0.1.3

so instead of a version on the master branch, choose a different branch name.

[francislavoie]

Right but you would do that with @ in the xcaddy command, but that doesn't work. Did you miss that in the post above (2nd code block)?

[mholt]

I mean do this instead:

xcaddy build --with github.com/francislavoie/caddy-dynamicdns@caddyfile

[francislavoie]

That won't work because the module in that repo is github.com/mholt/caddy-dynamicdns so a replace needs to happen.

[mholt]

Oh... I see... how does the go tool determine which kind of replacement to do, I wonder? (Can look into it later)

[francislavoie]

It does it just fine if you specify go mod edit -replace github.com/mholt/caddy-dynamicdns=/root/github.com/francislavoie/caddy-dynamicdns@caddyfile but the problem is our "relative path" resolve step breaks it at the xcaddy CLI layer. (this is all explained above)

[mohammed90]

FWIW, I started working on it last night but didn't finish it. This is where I'm at now.

Diff:

diff --git a/cmd/xcaddy/main.go b/cmd/xcaddy/main.go
index 001f462..39d8b72 100644
--- a/cmd/xcaddy/main.go
+++ b/cmd/xcaddy/main.go
@@ -76,7 +76,7 @@ func runBuild(ctx context.Context, args []string) error {
 			})
 			if repl != "" {
 				// adjust relative replacements in current working directory since our temporary module is in a different directory
-				if !filepath.IsAbs(repl) {
+				if strings.HasPrefix(repl, ".") && !filepath.IsAbs(repl) {
 					repl, err = filepath.Abs(repl)
 					if err != nil {
 						log.Fatalf("[FATAL] %v", err)
@@ -288,7 +288,9 @@ func trapSignals(ctx context.Context, cancel context.CancelFunc) {
 func splitWith(arg string) (module, version, replace string, err error) {
 	const versionSplit, replaceSplit = "@", "="
 
-	parts := strings.SplitN(arg, versionSplit, 2)
+	modules := strings.SplitN(arg, replaceSplit, 2)
+
+	parts := strings.SplitN(modules[0], versionSplit, 2)
 	module = parts[0]
 
 	if len(parts) == 1 {

Test run:

=== RUN   TestSplitWith
    caddyserver/xcaddy/cmd/xcaddy/main_test.go:72: Test 2: Expected module 'replace' but got '' (input='module@version=replace')
    caddyserver/xcaddy/cmd/xcaddy/main_test.go:72: Test 3: Expected module 'replace' but got '' (input='module=replace')

[francislavoie]

It also needs to support module=replace@version

[mohammed90]

It also needs to support module=replace@version

Hence

but didn't finish it

😄