1. The problem I’m having:
With curl/8.1.2, posting an azure alert json payload to caddy local host having a route /transform/test* with two handlers;
handler 1 -
my custom module, transforming json payload from azure alert to slack notification, increasing the payload length (from 767 to 1315)
handler 2 - reverse_proxy to slack web hook, reporting the error
I have tested an adjusted azure alert with length 1315 (adding dummy data), then everything is working with /transform/test*.
Is this use case, reverse_proxy of a transformed payload, kind of misuse?
If not, any advice?
Everything is in my repo
2. Error messages and/or full log output:
alert-t
2023/09/20 18:11:19.236 DEBUG http.handlers.az_alert_slack_notification before transformation {"request": {"remote_ip": "127.0.0.1", "remote_port": "62723", "client_ip": "127.0.0.1", "proto": "HTTP/1.1", "method": "POST", "host": "localhost", "uri": "/transform/test", "headers": {"User-Agent": ["curl/8.1.2"], "Accept": ["*/*"], "Content-Type": ["application/json"], "Content-Length": ["767"]}}}
2023/09/20 18:11:19.236 DEBUG http.handlers.az_alert_slack_notification before body {"body": "{\"schemaId\":\"azureMonitorCommonAlertSchema\",\"data\":{\"essentials\":{\"alertId\":\"/subscriptions/9876/providers/Microsoft.AlertsManagement/alerts/b9569717-bc32-442f-add5-83a997729330\",\"alertRule\":\"Test-Rule-1\",\"severity\":\"Sev4\",\"signalType\":\"Metric\",\"monitorCondition\":\"Fired\",\"monitoringService\":\"Platform\",\"alertTargetIDs\":[\"/subscriptions/1234/resourcegroups/pipelinealertrg/providers/microsoft.compute/virtualmachines/wcus-r2-gen2\"],\"configurationItems\":[\"wcus-r2-gen2\"],\"originAlertId\":\"3f2d4487-b0fc-4125-8bd5-7ad17384221e_PipeLineAlertRG_microsoft.insights_metricAlerts_WCUS-R2-Gen2_-117781227\",\"firedDateTime\":\"2019-03-22T13:58:24.3713213Z\",\"resolvedDateTime\":\"2019-03-22T14:03:16.2246313Z\",\"description\":\"\",\"essentialsVersion\":\"1.0\",\"alertContextVersion\":\"1.0\"}}}"}
2023/09/20 18:11:19.236 DEBUG http.handlers.az_alert_slack_notification transformed body {"body": "{\"blocks\":[{\"type\":\"divider\"},{\"type\":\"header\",\"text\":{\"type\":\"plain_text\",\"text\":\"New monitor alert!\",\"emoji\":true}},{\"type\":\"divider\"},{\"type\":\"actions\",\"elements\":[{\"type\":\"button\",\"text\":{\"type\":\"plain_text\",\"text\":\"View alert in Monitor\",\"emoji\":true},\"url\":\"https://portal.azure.com/#blade/Microsoft_Azure_Monitoring/AlertDetailsTemplateBlade/alertId/%2Fsubscriptions%2F9876%2Fproviders%2FMicrosoft.AlertsManagement%2Falerts%2Fb9569717-bc32-442f-add5-83a997729330\",\"style\":\"primary\"}]},{\"type\":\"header\",\"text\":{\"type\":\"plain_text\",\"text\":\"Summary\",\"emoji\":true}},{\"type\":\"divider\"},{\"type\":\"section\",\"fields\":[{\"type\":\"mrkdwn\",\"text\":\"Fired (UTC)\"},{\"type\":\"plain_text\",\"text\":\"2019-03-22T13:58:24.3713213Z\",\"emoji\":true},{\"type\":\"mrkdwn\",\"text\":\"Alert name\"},{\"type\":\"plain_text\",\"text\":\"Test-Rule-1\",\"emoji\":true},{\"type\":\"mrkdwn\",\"text\":\"Severity\"},{\"type\":\"plain_text\",\"text\":\":speech_balloon: Verbose(4)\",\"emoji\":true}]},{\"type\":\"header\",\"text\":{\"type\":\"plain_text\",\"text\":\"Resources\",\"emoji\":true}},{\"type\":\"divider\"},{\"type\":\"section\",\"fields\":[{\"type\":\"mrkdwn\",\"text\":\"\\u003chttps://portal.azure.com/#@nav.no/resource/subscriptions/1234/resourcegroups/pipelinealertrg/providers/microsoft.compute/virtualmachines/wcus-r2-gen2|wcus-r2-gen2\\u003e\"},{\"type\":\"plain_text\",\"text\":\":link:\",\"emoji\":true}]}]}"}
2023/09/20 18:11:19.237 DEBUG http.handlers.az_alert_slack_notification after transformation {"request": {"remote_ip": "127.0.0.1", "remote_port": "62723", "client_ip": "127.0.0.1", "proto": "HTTP/1.1", "method": "POST", "host": "localhost", "uri": "/transform/test", "headers": {"User-Agent": ["curl/8.1.2"], "Accept": ["*/*"], "Content-Type": ["application/json"], "Content-Length": ["1315"]}}}
2023/09/20 18:11:19.237 DEBUG http.handlers.reverse_proxy selected upstream {"dial": "hooks.slack.com:443", "total_upstreams": 1}
2023/09/20 18:11:19.382 DEBUG http.handlers.reverse_proxy upstream roundtrip {"upstream": "hooks.slack.com:443", "duration": 0.145030334, "request": {"remote_ip": "127.0.0.1", "remote_port": "62723", "client_ip": "127.0.0.1", "proto": "HTTP/1.1", "method": "POST", "host": "hooks.slack.com:443", "uri": "/services/secret/secret", "headers": {"X-Forwarded-For": ["127.0.0.1"], "X-Forwarded-Proto": ["http"], "X-Forwarded-Host": ["localhost"], "Content-Length": ["1315"], "User-Agent": ["curl/8.1.2"], "Accept": ["*/*"], "Content-Type": ["application/json"]}}, "error": "http2: request body larger than specified content length"}
2023/09/20 18:11:19.382 ERROR http.log.error http2: request body larger than specified content length {"request": {"remote_ip": "127.0.0.1", "remote_port": "62723", "client_ip": "127.0.0.1", "proto": "HTTP/1.1", "method": "POST", "host": "localhost", "uri": "/transform/test", "headers": {"Content-Length": ["767"], "User-Agent": ["curl/8.1.2"], "Accept": ["*/*"], "Content-Type": ["application/json"]}}, "duration": 0.145963458, "status": 502, "err_id": "zn45wg9fa", "err_trace": "reverseproxy.statusError (reverseproxy.go:1248)"}
HTTP/1.1 502 Bad Gateway
Server: Caddy
Date: Wed, 20 Sep 2023 18:11:19 GMT
Content-Length: 0
3. Caddy version:
v2.7.4 h1:J8nisjdOxnYHXlorUKXY75Gr6iBfudfoGhrJ8t7/flI=
4. How I installed and ran Caddy:
# in repo root
# new release of my module github.com/ttnesby/slack-block-builder/caddy-ext/azalertslacknotification
export def r-ca [] {
let ver = $in
gh release create ($ver) --notes "wip"
b-ca $ver
}
# build caddy with custom module, using xcaddy
export def b-ca [ver: string] {
let ext1 = $"github.com/ttnesby/slack-block-builder/caddy-ext/azalertslacknotification@($ver)"
~/go/bin/xcaddy build --with ($ext1)
}
# start caddy with Caddyfile
export def u-ca [] {
./caddy start Caddyfile
}
# stop caddy
export def d-ca [] {
./caddy stop
}
a. System environment:
macOS Ventura 13.5.2 (22G91)
GOHOSTARCH=‘arm64’
GOHOSTOS=‘darwin’
b. Command:
./caddy start Caddyfile
c. Service/unit/compose file:
d. My complete Caddy config:
{
log {
format console
level debug
}
}
(to-slack) {
reverse_proxy https://hooks.slack.com {
header_up Host {upstream_hostport}
rewrite {$SLACK_TEST_NOTIFICATION}
}
}
http://localhost {
#encode zstd gzip
# rate_limit details
# waf details
route /transform/test* {
az_alert_slack_notification
#respond {http.request.body}
import to-slack
}
route /direct/test* {
import to-slack
}
handle /health* {
respond "I'm fine" 200
}
}