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ddtrace/tracer: fixed precedence ordering of configuration options #1232

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merged 5 commits into from Apr 20, 2022
Merged

ddtrace/tracer: fixed precedence ordering of configuration options #1232

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f88aa2c
ddtrace/tracer: fixed precedence ordering of configuration options
dianashevchenko Apr 4, 2022
77eff54
removed redundant calls to resolveAgentAddr
dianashevchenko Apr 5, 2022
0974809
Refactored: removed inforcing of the code path; updated tests
dianashevchenko Apr 19, 2022
3978199
Merge branch 'v1' into shevchenko/config-precedence-order
dianashevchenko Apr 20, 2022
c6c82ed
Merge branch 'v1' into shevchenko/config-precedence-order
dianashevchenko Apr 20, 2022
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2 changes: 1 addition & 1 deletion ddtrace/tracer/option.go
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Expand Up @@ -177,7 +177,7 @@ func forEachStringTag(str string, fn func(key string, val string)) {
func newConfig(opts ...StartOption) *config {
c := new(config)
c.sampler = NewAllSampler()
c.agentAddr = resolveAgentAddr(defaultAddress)
c.agentAddr = resolveAgentAddr("")
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@gbbr gbbr Apr 5, 2022 •
edited

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Probably best to get rid of this completely and follow the same pattern as the other settings. We can move the env. var. checks together with the rest of the env. var checks for the other options.

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We would have to do it after running all the in-code options, I doubt that this change would contribute to cleaner code. Also, since it's in a separate function order of precedence is clear, no need to worry about someone moving around pieces of code

dd-trace-go/ddtrace/tracer/option.go

Lines 212 to 233 in 77eff54

forEachStringTag(v, func(key, val string) { WithServiceMapping(key, val)(c) })
}
if v := os.Getenv("DD_TAGS"); v != "" {
forEachStringTag(v, func(key, val string) { WithGlobalTag(key, val)(c) })
}
if _, ok := os.LookupEnv("AWS_LAMBDA_FUNCTION_NAME"); ok {
// AWS_LAMBDA_FUNCTION_NAME being set indicates that we're running in an AWS Lambda environment.
// See: https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html
c.logToStdout = true
}
c.logStartup = internal.BoolEnv("DD_TRACE_STARTUP_LOGS", true)
c.runtimeMetrics = internal.BoolEnv("DD_RUNTIME_METRICS_ENABLED", false)
c.debug = internal.BoolEnv("DD_TRACE_DEBUG", false)
c.enabled = internal.BoolEnv("DD_TRACE_ENABLED", true)
c.profilerEndpoints = internal.BoolEnv(traceprof.EndpointEnvVar, true)
c.profilerHotspots = internal.BoolEnv(traceprof.CodeHotspotsEnvVar, true)
for _, fn := range opts {
fn(c)
}
WithGlobalTag(ext.RuntimeID, globalconfig.RuntimeID())(c)
if c.env == "" {

As for the regression test, we have up to date TestResolveAgentAddr, which verify correct order of in-code options, env variables, and default values.

dd-trace-go/ddtrace/tracer/transport_test.go

Lines 80 to 88 in 77eff54

func TestResolveAgentAddr(t *testing.T) {
for _, tt := range []struct {
in, envHost, envPort, out string
}{
{"host", "", "", fmt.Sprintf("host:%s", defaultPort)},
{"www.my-address.com", "", "", fmt.Sprintf("www.my-address.com:%s", defaultPort)},
{"localhost", "", "", fmt.Sprintf("localhost:%s", defaultPort)},
{":1111", "", "", fmt.Sprintf("%s:1111", defaultHostname)},
{"", "", "", defaultAddress},

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@gbbr gbbr Apr 5, 2022 •
edited

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As for the regression test, we have up to date TestResolveAgentAddr, which verify correct order of in-code options, env variables, and default values.

Great! I didn't notice it at first, the Github diff was not too great.

[...] I doubt that this change would contribute to cleaner code [...]

It's about being consistent. Also, you are passing an empty string to a function which is not used anywhere else and technically its argument has no value. You are intentionally passing bad input to force a certain code path. I don't think that's the right approach. It's an old piece of code. Better to get rid of it and be consistent. Or am I missing something? Why do we need it?

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I reckon it's better to have the logic in the separate function, because otherwise 'configuration precedence order' relies only on the position in the code, which could be changed accidentaly in the future. Instead, I'll remove the arguments to the resolveAddr func and update tests according to that

c.httpClient = defaultHTTPClient()

if internal.BoolEnv("DD_TRACE_ANALYTICS_ENABLED", false) {
Expand Down
16 changes: 8 additions & 8 deletions ddtrace/tracer/transport.go
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Expand Up @@ -101,8 +101,8 @@ func newHTTPTransport(addr string, client *http.Client) *httpTransport {
defaultHeaders["Datadog-Container-ID"] = cid
}
return &httpTransport{
traceURL: fmt.Sprintf("http://%s/v0.4/traces", resolveAgentAddr(addr)),
statsURL: fmt.Sprintf("http://%s/v0.6/stats", resolveAgentAddr(addr)),
traceURL: fmt.Sprintf("http://%s/v0.4/traces", addr),
statsURL: fmt.Sprintf("http://%s/v0.6/stats", addr),
client: client,
headers: defaultHeaders,
}
Expand Down Expand Up @@ -192,17 +192,17 @@ func resolveAgentAddr(addr string) string {
// no port in addr
host = addr
}
if v := os.Getenv("DD_AGENT_HOST"); v != "" && host == "" {
host = v
}
if v := os.Getenv("DD_TRACE_AGENT_PORT"); v != "" && port == "" {
port = v
}
if host == "" {
host = defaultHostname
}
if port == "" {
port = defaultPort
}
if v := os.Getenv("DD_AGENT_HOST"); v != "" {
host = v
}
if v := os.Getenv("DD_TRACE_AGENT_PORT"); v != "" {
port = v
}
return fmt.Sprintf("%s:%s", host, port)
}
15 changes: 8 additions & 7 deletions ddtrace/tracer/transport_test.go
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Expand Up @@ -87,16 +87,17 @@ func TestResolveAgentAddr(t *testing.T) {
{":1111", "", "", fmt.Sprintf("%s:1111", defaultHostname)},
{"", "", "", defaultAddress},
{"custom:1234", "", "", "custom:1234"},
{"", "", "", defaultAddress},
{"", "ip.local", "", fmt.Sprintf("ip.local:%s", defaultPort)},
{"", "", "1234", fmt.Sprintf("%s:1234", defaultHostname)},
{"", "ip.local", "1234", "ip.local:1234"},
{"ip.other", "ip.local", "", fmt.Sprintf("ip.local:%s", defaultPort)},
{"ip.other:1234", "ip.local", "", "ip.local:1234"},
{":8888", "", "1234", fmt.Sprintf("%s:1234", defaultHostname)},
{"ip.other:8888", "", "1234", "ip.other:1234"},
{"ip.other", "ip.local", "1234", "ip.local:1234"},
{"ip.other:8888", "ip.local", "1234", "ip.local:1234"},
{"ip.other", "ip.local", "", fmt.Sprintf("ip.other:%s", defaultPort)},
{"ip.other:1234", "ip.local", "", "ip.other:1234"},
{":8888", "", "1234", fmt.Sprintf("%s:8888", defaultHostname)},
{"ip.other:8888", "", "1234", "ip.other:8888"},
{"ip.other", "ip.local", "1234", "ip.other:1234"},
{"ip.other:8888", "ip.local", "1234", "ip.other:8888"},
{"ip.other", "ip.local", "1234", fmt.Sprintf("ip.other:%v", 1234)},
{"ip.other:1234", "ip.local", "", "ip.other:1234"},
} {
t.Run("", func(t *testing.T) {
if tt.envHost != "" {
Expand Down