1. A system comprising: one or more memory units with executable instructions; and one or more processing units that, when executing the instructions in the one or more memory units, are operable to: receive an application definition associated with an ad hoc application provisioned from one or more computing resources delivered over a network, the application definition identifying a first group of components, the first group of components comprising the ad hoc application and one or more computing resources relied on by the ad hoc application; receive tag information from a user, the tag information indicating one or more aspects of the first group of components; access infrastructure data from an infrastructure repository, the infrastructure data identifying a second group of components, the second group of components comprising one or more computing resources of a distributed architecture that are associated with at least a subset of one or more components in the first group of components; generate a plurality of conditional probability tables, one conditional probability table for at least a first subset of the components in the first group of components and at least a second subset of the second group of components, the plurality of conditional probability tables identifying at least an availability of a respective component of at least the first subset of the first group of components or at least the second subset of the second group of components based at least in part on a second availability of one or more relied upon components of the first group of components or the second group of component, where the one or more relied upon components are components utilized, at least in part, during operation of the respective component; and based at least in part on the plurality of conditional probability tables, calculate a reliability estimate for the ad hoc application by at least performing a plurality of trials, wherein performing the plurality of trials comprises assigning a status of either available or not available to at least a portion of the components in a directed graph, the status based at least in part on a particular conditional probability table associated with a particular component and the status of one or more directly relied upon components.