Add a new setting for configuring hostname

README.md

@@ -416,6 +416,13 @@ These settings can be changed at any time.
 
 #### Network settings
 
+* `settings.network.hostname`: The desired hostname of the system.
+  **Important note for all Kubernetes variants:** Changing this setting at runtime (not via user data) can cause issues with kubelet registration, as hostname is closely tied to the identity of the system for both registration and certificates/authorization purposes.
+
+Most users don't need to change this setting as the following defaults work for the majority of use cases.
+If this setting isn't set we attempt to use DNS reverse lookup for the hostname.
+If the lookup is unsuccessful, the IP of the node is used in the format `ip-X-X-X-X`.
+
 ##### Proxy settings
 
 These settings will configure the proxying behavior of the following services:

Release.toml

@@ -59,3 +59,7 @@ version = "1.1.4"
     "migrate_v1.1.3_kubelet-cpu-manager.lz4",
 ]
 "(1.1.3, 1.1.4)" = []
+"(1.1.4, 1.1.5)" = [
+    "migrate_v1.1.5_hostname-setting.lz4",
+    "migrate_v1.1.5_hostname-setting-metadata.lz4",
+]

packages/release/hostname-env

@@ -0,0 +1 @@
+HOSTNAME={{settings.network.hostname}}

packages/release/release.spec

@@ -14,13 +14,15 @@ Source99: release-tmpfiles.conf
 
 Source200: motd.template
 Source201: proxy-env
+Source202: hostname-env
 
 Source1000: eth0.xml
 Source1001: multi-user.target
 Source1002: configured.target
 Source1003: preconfigured.target
 Source1004: activate-configured.service
 Source1005: activate-multi-user.service
+Source1011: set-hostname.service
 
 # Mounts for writable local storage.
 Source1006: var.mount
@@ -108,7 +110,7 @@ EOF
 install -d %{buildroot}%{_cross_unitdir}
 install -p -m 0644 \
   %{S:1001} %{S:1002} %{S:1003} %{S:1004} %{S:1005} \
-  %{S:1006} %{S:1007} %{S:1008} %{S:1009} %{S:1010} \
+  %{S:1006} %{S:1007} %{S:1008} %{S:1009} %{S:1010} %{S:1011} \
   %{S:1015} %{S:1040} %{S:1041} %{S:1060} %{S:1061} %{S:1062} \
   %{buildroot}%{_cross_unitdir}
 
@@ -129,6 +131,7 @@ install -p -m 0644 ${LICENSEPATH}.mount %{buildroot}%{_cross_unitdir}
 install -d %{buildroot}%{_cross_templatedir}
 install -p -m 0644 %{S:200} %{buildroot}%{_cross_templatedir}/motd
 install -p -m 0644 %{S:201} %{buildroot}%{_cross_templatedir}/proxy-env
+install -p -m 0644 %{S:202} %{buildroot}%{_cross_templatedir}/hostname-env
 
 install -d %{buildroot}%{_cross_udevrulesdir}
 install -p -m 0644 %{S:1016} %{buildroot}%{_cross_udevrulesdir}/61-mount-cdrom.rules
@@ -163,9 +166,11 @@ ln -s %{_cross_unitdir}/preconfigured.target %{buildroot}%{_cross_unitdir}/defau
 %{_cross_unitdir}/*-kernels.mount
 %{_cross_unitdir}/*-licenses.mount
 %{_cross_unitdir}/var-lib-bottlerocket.mount
+%{_cross_unitdir}/set-hostname.service
 %dir %{_cross_templatedir}
 %{_cross_templatedir}/motd
 %{_cross_templatedir}/proxy-env
+%{_cross_templatedir}/hostname-env
 %{_cross_udevrulesdir}/61-mount-cdrom.rules
 
 %changelog

packages/release/set-hostname.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=Sets the hostname
+After=settings-applier.service
+Requires=settings-applier.service
+
+[Service]
+Type=oneshot
+EnvironmentFile=/etc/network/hostname.env
+ExecStart=/usr/bin/netdog set-hostname '${HOSTNAME}'
+RemainAfterExit=true
+StandardError=journal+console
+
+[Install]
+WantedBy=preconfigured.target

sources/Cargo.toml

@@ -37,6 +37,8 @@ members = [
     "api/migration/migrations/v1.1.2/control-container-v0-5-1",
     "api/migration/migrations/v1.1.3/kubelet-cpu-manager-state",
     "api/migration/migrations/v1.1.3/kubelet-cpu-manager",
+    "api/migration/migrations/v1.1.5/hostname-setting",
+    "api/migration/migrations/v1.1.5/hostname-setting-metadata",
 
     "bottlerocket-release",
 

sources/api/migration/migrations/v1.1.5/hostname-setting-metadata/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "hostname-setting-metadata"
+version = "0.1.0"
+authors = ["Zac Mrowicki <[email protected]>"]
+license = "Apache-2.0 OR MIT"
+edition = "2018"
+publish = false
+# Don't rebuild crate just because of changes to README.
+exclude = ["README.md"]
+
+[dependencies]
+migration-helpers = { path = "../../../migration-helpers" }

sources/api/migration/migrations/v1.1.5/hostname-setting-metadata/src/main.rs

@@ -0,0 +1,23 @@
+#![deny(rust_2018_idioms)]
+
+use migration_helpers::common_migrations::{AddMetadataMigration, SettingMetadata};
+use migration_helpers::{migrate, Result};
+use std::process;
+
+/// We added a new setting and generator for configuring hostname
+fn run() -> Result<()> {
+    migrate(AddMetadataMigration(&[SettingMetadata {
+        metadata: &["setting-generator", "affected-services"],
+        setting: "settings.network.hostname",
+    }]))
+}
+
+// Returning a Result from main makes it print a Debug representation of the error, but with Snafu
+// we have nice Display representations of the error, so we wrap "main" (run) and print any error.
+// https://github.com/shepmaster/snafu/issues/110
+fn main() {
+    if let Err(e) = run() {
+        eprintln!("{}", e);
+        process::exit(1);
+    }
+}

sources/api/migration/migrations/v1.1.5/hostname-setting/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "hostname-setting"
+version = "0.1.0"
+authors = ["Zac Mrowicki <[email protected]>"]
+license = "Apache-2.0 OR MIT"
+edition = "2018"
+publish = false
+# Don't rebuild crate just because of changes to README.
+exclude = ["README.md"]
+
+[dependencies]
+migration-helpers = { path = "../../../migration-helpers" }

sources/api/migration/migrations/v1.1.5/hostname-setting/src/main.rs

@@ -0,0 +1,24 @@
+#![deny(rust_2018_idioms)]
+
+use migration_helpers::common_migrations::AddPrefixesMigration;
+use migration_helpers::{migrate, Result};
+use std::process;
+
+/// We added a new setting and generator for configuring hostname
+fn run() -> Result<()> {
+    migrate(AddPrefixesMigration(vec![
+        "settings.network.hostname",
+        "services.hostname",
+        "configuration-files.hostname",
+    ]))
+}
+
+// Returning a Result from main makes it print a Debug representation of the error, but with Snafu
+// we have nice Display representations of the error, so we wrap "main" (run) and print any error.
+// https://github.com/shepmaster/snafu/issues/110
+fn main() {
+    if let Err(e) = run() {
+        eprintln!("{}", e);
+        process::exit(1);
+    }
+}

sources/api/netdog/Cargo.toml

@@ -9,6 +9,7 @@ publish = false
 exclude = ["README.md"]
 
 [dependencies]
+argh = "0.1.4"
 dns-lookup = "1.0"
 ipnet = { version = "2.0", features = ["serde"] }
 envy = "0.4"

sources/api/netdog/README.md

@@ -4,11 +4,16 @@ Current version: 0.1.0
 
 ## Introduction
 
-netdog is a small helper program for wicked, to apply network settings received from DHCP.  It also
-contains a subcommand `node-ip` that returns the node's current IP address in JSON format; this
-subcommand is intended for use as a settings generator.
+netdog is a small helper program for wicked, to apply network settings received from DHCP.  It
+generates `/etc/resolv.conf`, generates and sets the hostname, and persists the current IP to a
+file.
 
-It generates `/etc/resolv.conf`, sets the hostname, and persists the current IP to file.
+It contains two subcommands meant for use as settings generators:
+* `node-ip`: returns the node's current IP address in JSON format
+* `generate-hostname`: returns the node's hostname in JSON format (it is the resolved IP or the IP
+  in format "ip-x-x-x-x" if resolving fails)
+
+The subcommand `set-hostname` sets the hostname for the system.
 
 ## Colophon