A better diag policy for app service
I have long wanted to find the time to revisit refactoring the built-in version of diagnostic policy for app service. As this exhibits a couple of issues I want to tackle.
- Remove as much of the tendency to use hardcoded values multiple places in the policy. Making maintenance more easy.
- Add ways to filter out different types of app services based on something like tags.
- add more dynamic ways to pull data from the service at runtime to make better choices.
What I came up with is the following:
- Move definition of metric/log category names to monitor to parameters
- Dont use log category names directly in the template, but reference parameter list insted. This makes maintenance easier to track.
- Add filter option on tags to give the option to only include some app services. Like env = prod
- Use runtime information from the app service itself, so the policy can determine dynamically what log categories are available on each instance processed.
This is what I came up with (JSON format):
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 | { "properties": { "displayName": "Deploy Diagnostics AppService", "policyType": "Custom", "mode": "Indexed", "metadata": { "category": "Monitoring" }, "version": "1.0.0", "parameters": { "logAnalytics": { "type": "String", "metadata": { "displayName": "Log Analytics workspace", "description": "Select Log Analytics workspace from dropdown list. If this workspace is outside of the scope of the assignment you must manually grant 'Log Analytics Contributor' permissions (or similar) to the policy assignment's principal ID.", "strongType": "omsWorkspace" } }, "effect": { "type": "String", "metadata": { "displayName": "Effect", "description": "Enable or disable the execution of the policy" }, "allowedValues": [ "DeployIfNotExists", "Disabled" ], "defaultValue": "DeployIfNotExists" }, "profileName": { "type": "String", "metadata": { "displayName": "Profile name", "description": "The diagnostic settings profile name" }, "defaultValue": "Eunomia-Operations" }, "metricsEnabled": { "type": "Array", "metadata": { "displayName": "Metrics to enable", "description": "Whether to enable metrics stream to the Log Analytics workspace. AllMetrics or None. Future support for multiple categories" }, "allowedValues": [ "None", "AllMetrics" ], "defaultValue": [ "AllMetrics" ] }, "logsEnabled": { "type": "Array", "metadata": { "displayName": "Logs to enable", "description": "Name of logs to enable for web app, supports multiple selections. Use syntax: AppServiceHTTPLogs;AppServiceAppLogs. Or just AllLogs or None." }, "allowedValues": [ "None", "AllLogs", "AppServiceConsoleLogs", "AppServiceHTTPLogs", "AppServiceAuditLogs", "AppServiceFileAuditLogs", "AppServiceAppLogs", "AppServiceIPSecAuditLogs", "AppServicePlatformLogs", "AppServiceAntivirusScanAuditLogs", "AppServiceAuthenticationLogs" ], "defaultValue": [ "AllLogs" ] }, "stdLogCategories": { "type": "Array", "metadata": { "displayName": "List of non premium log categories", "description": "Add all non premium log category names, it is used in compliancy calculation" }, "allowedValues": [ "AppServiceConsoleLogs", "AppServiceHTTPLogs", "AppServiceAuditLogs", "AppServiceAppLogs", "AppServiceIPSecAuditLogs", "AppServicePlatformLogs", "AppServiceAuthenticationLogs" ], "defaultValue": [ "AppServiceConsoleLogs", "AppServiceHTTPLogs", "AppServiceAuditLogs", "AppServiceAppLogs", "AppServiceIPSecAuditLogs", "AppServicePlatformLogs", "AppServiceAuthenticationLogs" ] }, "evaluationDelay": { "type": "String", "metadata": { "displayName": "Evaluation Delay", "description": "Specifies when the existence of the related resources should be evaluated. The delay is only used for evaluations that are a result of a create or update resource request. Allowed values are AfterProvisioning, AfterProvisioningSuccess, AfterProvisioningFailure, or an ISO 8601 duration between 0 and 360 minutes." }, "defaultValue": "PT5M" }, "tagNameFilter": { "type": "String", "metadata": { "displayName": "Tag Name to filter for", "description": "Tag name to match for." }, "defaultValue": "all" }, "tagValueFilter": { "type": "String", "metadata": { "displayName": "Tag value to filter for", "description": "Tag value to match for." }, "defaultValue": "all" } }, "policyRule": { "if": { "allOf": [ { "field": "type", "equals": "Microsoft.Web/sites" }, { "field": "kind", "notLike": "functionapp*" }, { "field": "kind", "notLike": "api*" }, { "field": "kind", "notLike": "ase*" }, { "anyOf": [ { "field": "[concat('tags[', parameters('tagNameFilter'), ']')]", "equals": "[parameters('tagValueFilter')]" }, { "value": "[parameters('tagNameFilter')]", "equals": "all" } ] } ] }, "then": { "effect": "[parameters('effect')]", "details": { "type": "Microsoft.Insights/diagnosticSettings", "name": "[parameters('profileName')]", "evaluationDelay": "[parameters('evaluationDelay')]", "roleDefinitionIds": [ "/providers/microsoft.authorization/roleDefinitions/749f88d5-cbae-40b8-bcfc-e573ddc772fa", "/providers/microsoft.authorization/roleDefinitions/92aaf0da-9dab-42b6-94a3-d43ce8d16293" ], "existenceCondition": { "allOf": [ { "anyOf": [ { "field": "Microsoft.Insights/diagnosticSettings/logs.enabled", "equals": "[if(contains(parameters('logsEnabled'),'AllLogs'),'True','Skipped')]" }, { "field": "Microsoft.Insights/diagnosticSettings/logs.enabled", "equals": "[if(contains(parameters('logsEnabled'),'None'),'False','Skipped')]" }, { "count": { "field": "Microsoft.Insights/diagnosticSettings/logs[*]", "where": { "allOf": [ { "value": "[current('Microsoft.Insights/diagnosticSettings/logs[*].enabled')]", "equals": "True" }, { "value": "[current('Microsoft.Insights/diagnosticSettings/logs[*].category')]", "in": "[if(or(contains(parameters('logsEnabled'),'AllLogs'),contains(parameters('logsEnabled'),'None')),array(''),parameters('logsEnabled'))]" } ] } }, "equals": "[if(or(contains(parameters('logsEnabled'),'AllLogs'),contains(parameters('logsEnabled'),'None')),-1,if(greater(length(field('Microsoft.Insights/diagnosticSettings/logs[*].category')),length(parameters('stdLogCategories'))),length(parameters('logsEnabled')),length(intersection(parameters('logsEnabled'),parameters('stdLogCategories')))))]" } ] }, { "field": "Microsoft.Insights/diagnosticSettings/metrics.enabled", "equals": "[contains(parameters('metricsEnabled'),'AllMetrics')]" }, { "field": "Microsoft.Insights/diagnosticSettings/workspaceId", "matchInsensitively": "[parameters('logAnalytics')]" } ] }, "deployment": { "properties": { "mode": "incremental", "template": { "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#", "contentVersion": "1.0.0.0", "parameters": { "profileName": { "type": "string" }, "resourceName": { "type": "string" }, "logAnalytics": { "type": "string" }, "metricsEnabled": { "type": "array" }, "logsEnabled": { "type": "array" }, "location": { "type": "string" } }, "variables": {}, "resources": [ { "type": "Microsoft.Resources/deployments", "apiVersion": "2024-03-01", "name": "[concat('diag_web_app_parent_',parameters('resourceName'),'_',parameters('profileName'))]", "properties": { "mode": "Incremental", "expressionEvaluationOptions": { "scope": "inner" }, "parameters": { "resourceLogCategories": { "value": "[split(replace(reference(resourceId('Microsoft.Web/sites', parameters('resourceName')),'2022-09-01').eligibleLogCategories, ',ScanLogs', ''),',')]" }, "profileName": { "value": "[parameters('profileName')]" }, "logAnalytics": { "value": "[parameters('logAnalytics')]" }, "metricsEnabled": { "value": "[parameters('metricsEnabled')]" }, "logsEnabled": { "value": "[parameters('logsEnabled')]" }, "location": { "value": "[parameters('location')]" }, "resourceName": { "value": "[parameters('resourceName')]" } }, "template": { "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#", "contentVersion": "1.0.0.0", "parameters": { "resourceLogCategories": { "type": "array" }, "profileName": { "type": "string" }, "resourceName": { "type": "string" }, "logAnalytics": { "type": "string" }, "metricsEnabled": { "type": "array" }, "logsEnabled": { "type": "array" }, "location": { "type": "string" } }, "resources": [ { "type": "Microsoft.Web/sites/providers/diagnosticSettings", "apiVersion": "2021-05-01-preview", "name": "[concat(parameters('resourceName'), '/', 'Microsoft.Insights/', parameters('profileName'))]", "location": "[parameters('location')]", "dependsOn": [], "properties": { "workspaceId": "[parameters('logAnalytics')]", "copy": [ { "name": "metrics", "count": "[length(parameters('metricsEnabled'))]", "input": { "category": "[parameters('metricsEnabled')[copyIndex('metrics')]]", "timeGrain": null, "enabled": "[contains(parameters('metricsEnabled'),'AllMetrics')]", "retentionPolicy": { "days": 0, "enabled": false } } }, { "name": "logs", "count": "[length(parameters('resourceLogCategories'))]", "input": { "category": "[parameters('resourceLogCategories')[copyIndex('logs')]]", "enabled": "[or(contains(parameters('logsEnabled'),parameters('resourceLogCategories')[copyIndex('logs')]),contains(parameters('logsEnabled'),'AllLogs'))]" } } ] } } ] } } } ], "outputs": { "policy": { "type": "string", "value": "[concat('Diagnostic setting name: ', parameters('profileName'), ', resourceName: ', parameters('resourceName'), ' to Log Analytics: ', parameters('logAnalytics'), ' configured')]" } } }, "parameters": { "profileName": { "value": "[parameters('profileName')]" }, "logAnalytics": { "value": "[parameters('logAnalytics')]" }, "metricsEnabled": { "value": "[parameters('metricsEnabled')]" }, "logsEnabled": { "value": "[parameters('logsEnabled')]" }, "location": { "value": "[field('location')]" }, "resourceName": { "value": "[field('name')]" } } } } } } }, "versions": [ "1.0.0" ] }, "type": "Microsoft.Authorization/policyDefinitions", "name": "Deploy-Diagnostics-AppService-Custom", } |
What is nice is that this structure can be adopted for other services also.